On 4 February 2013 12:03, Soichi Ishida = <lists@ruby-fo= rum.com> wrote:

Thanks everyone. They will certainly help.
In addition to these, what if I want to apply specific regular
expressions to each of the lines?

say,

if line =3D~ /exp1/ then
=A0# do stuff
else
=A0# do stuff
end

In this case, the loop for all lines must be implemented, am I correct?
=

The previous code already does that,= and we showed that it can be done in one loop.

=A0

If the class methods dynamically take regular expression like

test =3D DataExtractor.new('file.txt')
test.apply_regexp(/exp1/)

Doesn't the loop need to be reactivated for each method like this?

=A0

Yes, if the regex isn't necessarily kn= own beforehand you'll have to do the loop again once it is known. =A0No= te that, as Marcus pointed out, you're reading the file into memory; if= you are happy trading IO delays for permanent memory usage, you could stor= e the file contents in an instance variable (either in the constructor or l= azily) and then perform your variable pattern match on the stored file cont= ents. =A0It would still need to perform the loop many times, but would save= a lot of time in the #open and #read phases.

There are other caching techniques, as well= , if you think a particular pattern is likely to be tested multiple times. = =A0Probably a bit advanced for this discussion, though.

--
=A0 Matthew Kerwin, B.Sc (CompSci) (Hons)
=A0 http://matthew.kerwin.net.au= /
=A0 ABN: 59-013-727-651

=A0 "You'll never find a p= rogramming language that frees
=A0 you from the burden of clarifying your ideas." - xkcd